This invention pertains to both a novel and to a useful dosage form. Particularly, the invention relates to a dosage form capable of changing its shape. More particularly, the invention concerns a dosage form comprising a drug and means that respond to a physical-chemical influence, whereby the dosage form changes from an initial to a total drug delivery shape.
Dosage forms, and more particularly osmotic dosage forms were disclosed by Theeuwes and Higuchi in U.S. Pat. Nos. 3,845,770 and 3,916,899. The dosage forms disclosed in these patents comprise a wall that surround a therapeutic drug. The wall is permeable to the passage of an external fluid, and it is substantially impermeable to the passage of drug. The dosage forms comprise a passageway through the wall for delivering the drug from the dosage form. These dosage forms release the drug by fluid being imbibed through the wall into the dosage form at a rate determined by the permeability of the wall and the osmotic pressure gradient across the wall. The dosage form thereby produces an aqueous solution containing the drug that is dispensed through the passage way from the dosage form. These dosage forms are effective extraordinarily for delivering a drug that is soluble in fluid and exhibits an osmotic pressure gradient across the wall against an external fluid.
A pioneer advancement in dosage forms was presented to the pharmaceutical-dispensing arts by inventor Theeuwes in U.S. Pat. No. 4,111,202. In this patent, the delivery kinetics of the osmotic dosage form is enhanced for delivering a drug that is insoluble to very soluble in fluid, by manufacturing the dosage form with a drug compartment and a displacement compartment separated by a piston. The piston is movable from a first rested to a second rested state. The osmotic dosage form delivers the drug by fluid imbibed through the wall of the dosage form into the displacement compartment thereby producing a solution that acts as a driving force that is applied against the piston. This force urges the piston to move against the drug compartment and correspondingly displace the drug through a passageway from the dosage form. While this dosage form operates successfully for its intended use, and while it can deliver many drugs of varying solubilities, its use can be limited, because of the complex manufacturing steps and the high cost needed for fabricating and placing the piston in the dosage form.
In U.S. Pat. No. 4,327,725 patentees Cortese and Theeuwes provided an osmotic dosage form for delivering a therapeutic agent that because of its solubility in aqueous and biological fluids, is difficult to deliver in therapeutic doses at a controlled rate over time. The dosage form of this patent comprises a wall that is semipermeable. The semipermeable wall surrounds a compartment containing a therapeutic agent that is insoluble to very soluble in aqueous and biological fluids and a separate osmogel. In operation, the osmogel, a hydrogel, expands in the presence of external fluid that enters the dosage form thereby causing the beneficial agent to be dispensed through a passageway from the dosage form. This dosage form operates successfully for its intended use, and it delivers many difficult to deliver therapeutic agents for their intended therapy.
Now, it has been observed unexpectedly, the above presented dosage forms may not deliver their intended dose of therapeutic agent, including a drug. This observation that these dosage forms may not achieve their full delivery potential is attributed to limitations in the prior art dosage forms. For instance, the dosage forms may not deliver all of the needed dose, and the prior art sought to compensate for this inherent limitation by manufacturing the dosage form containing an over dose of drug. This over dose or excess dose, often became trapped in the dosage form, or it led to dose dumping of the drug. The dose dumping is accompanied by over medication that may give rise to unwanted side effects. Then too, an osmogel in the dosage form may be restricted from its maximum expansion for displacing a drug from the dosage form due to the rigidity or lack of flexibility of the membrane of the dosage form.
It will be appreciated by those versed in the drug dispensing art, that if a dosage from can be provided that delivers all of its intended dose, substantially free of a over dose of drug, such a dosage form would have a positive value and also represent an advancement in the dispensing art. Likewise, it will be appreciated by those versed in the dispensing art, that if a novel dosage form is made available possessing physical properties for delivering a prescribed need dose of drug substantially-free of drug overage, the novel dosage form would find an immediate and practical application in the fields of pharmacy and medicine.
Accordingly, in view of the above presentation, it is an immediate object of this invention to provide a novel and nonobvious dosage form that represents an improvement and an advancement in the dispensing arts.
Another object of the invention is to provide an osmotic system manufactured as a dosage form that overcomes the disadvantages and limitations associated with the prior art dosage forms.
Another object of the invention is to make available a dosage form that delivers the required and needed dose of drug for accepted therapy free of delivering an overage of drug.
Another object of the invention is to provide a dosage form that keeps its physical integrity while delivering a therapeutic dose of drug while avoiding and/or reducing the risks associated with dose dumping of the drug.
Another object of the invention is to provide a dosage form comprising means for changing from a rested state to a flexible state and can deliver a dose of drug at a controlled-rate over a sustained release period of time.
Another object of the invention is to provide a new and useful dosage form that attains a zero-order release drug delivery profile while administering a drug to a human patient.
Another object of the invention is to make available a dosage form which dosage form during a drug delivery period is free from fractures and thereby avoids delivering a full dose of drug plus any drug overages in a shorter than the desired delivery time.
Another object of the invention is to provide a dosage form comprising a membrane that is flexible and thereby enable the dosage form to change its shape and thereby deliver essentially its total content of drug.
Another object of the invention is to provide a dosage form comprising a membrane endowed with a high concentration of plasticizer that enables the membrane to undergo change from a fixed, rigid non-rounded shape to a flexible rounded shape and thereby enhance the delivery of drug from the dosage form.
Another object of the invention is to provide a osmotic delivery system manufactured as a dosage form that can administer a complete pharmaceutical dosage regimen at a controlled rate and at a sustained-release rate for a particular time period, the use of which requires intervention only for the initiation and possible termination of the regimen.
Other objects, features, aspects and advantages of the invention will be more apparent to those skilled in the dispensing art from the following detailed specification taken in conjunction with the accompanying figures and accompanying claims.